Maciel P O, Alves R R
Empresa Brasileira de Pesquisa Agropecuária, Embrapa Pesca e Aquicultura, Postal Box 90, 77008-900, Palmas, TO, Brazil.
J Helminthol. 2018 Oct 26;94:e4. doi: 10.1017/S0022149X18000901.
Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas, providing basic biological data for D. cycloancistrium.
环钩盘虫（Dawestrema cycloancistrium）是导致亚马逊水产养殖中巨骨舌鱼（Arapaima gigas）鱼苗死亡的主要体外寄生虫。目前对于环钩盘虫的繁殖指数以及收集虫卵进行研究的合适方法知之甚少。本研究旨在确定环钩盘虫的产卵率。为实现这一目标，测试了两种虫卵定量方法：估计法（ME）和全计数法（MT）。与全计数法相比，估计法高估了计数的虫卵数量，估计法计数的虫卵数量为2943.5±2840.6个，全计数法为1041.5±533个；估计法的产卵率为80.1±58.7个/寄生虫/天，全计数法为31.4±16.4个/寄生虫/天。这些结果表明，对于量化环钩盘虫虫卵的研究，必须对样本中的所有虫卵进行计数，因为使用子样本进行的估计不具有代表性。使用全计数法，确定环钩盘虫的产卵率为每个成年寄生虫每天31.4±16.4个卵。本研究展示了巨骨舌鱼单殖吸虫类寄生虫的产卵能力，为环钩盘虫提供了基础生物学数据。
